Online ISSN
1350-911X
Print ISSN
0013-5194
Electronics Letters
Volume 6, Issue 8, 16 April 1970
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Volume 6, Issue 8
16 April 1970
Calculating step and impulse responses of networks
- Author(s): D.T. Bickley
- Source: Electronics Letters, Volume 6, Issue 8, p. 225 –226
- DOI: 10.1049/el:19700157
- Type: Article
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An economical method is given for calculating the step response, impulse response and derivatives of the impulse response of a network from a single partial-fraction expansion of the transfer function.
Parallel cellular floating-point multiplier
- Author(s): L. Frécon
- Source: Electronics Letters, Volume 6, Issue 8, p. 226 –228
- DOI: 10.1049/el:19700158
- Type: Article
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A cell is defined as a modified full adder. Such a cell allows the design of a multiplier, which handles signed floating point numbers.
High-speed gallium-arsenide Schottky-barrier field-effect transistors
- Author(s): K.E. Drangeid ; R. Sommerhalder ; W. Walter
- Source: Electronics Letters, Volume 6, Issue 8, p. 228 –229
- DOI: 10.1049/el:19700159
- Type: Article
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The letter shows that gallium arsenide is a well suited material for high-frequency field-effect transistors. From preliminary measurements on realised transistors, it is shown that the frequency limit for power amplification is considerably higher than for other known transistors. The processes involved are briefly described.
Fused logic: improved universal element and a trainable and gate
- Author(s): R. Baker
- Source: Electronics Letters, Volume 6, Issue 8, p. 229 –230
- DOI: 10.1049/el:19700160
- Type: Article
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A universal logic element is described whose performance is specified by fusing links. It is trained by presenting inputs specifying directly the minterms required in the final response. A trainable fused AND gate is also described which learns to respond to an input after being exposed to it.
Recent developments in magnetic levitation
- Author(s): B.Z. Kaplan
- Source: Electronics Letters, Volume 6, Issue 8, p. 230 –231
- DOI: 10.1049/el:19700161
- Type: Article
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New developments in magnetic levitation by tuned circuits are described. Suspension of relatively large weights at low frequencies is now possible. The system is extremely simple and therefore reliable. Owing to the high reliability and cylindrical symmetry, the levitation is suitable for magnetic bearings.
More rigorous proof of the thermal-noise formula for double injection diodes for ωτ ≫ 1
- Author(s): A. Van der Ziel
- Source: Electronics Letters, Volume 6, Issue 8, p. 231 –232
- DOI: 10.1049/el:19700162
- Type: Article
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A more rigorous proof of the thermal-noise formula for double-injection diodes for ωτ ≫ 1 is given, starting from the basic equations of the device.
Novel static Ward Leonard system
- Author(s): R.J. Castell ; A.R. Daniels ; J. La Trobe Exon
- Source: Electronics Letters, Volume 6, Issue 8, p. 232 –233
- DOI: 10.1049/el:19700163
- Type: Article
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A static Ward Leonard system is described which is fully capable of four-quadrant operation. Although both the forward and the reverse thyristor convertors are maintained in conduction simultaneously, the problems normally encountered with circulating currents do not arise.
Factorisation result for optimal discrete-time systems
- Author(s): D.H. Mee
- Source: Electronics Letters, Volume 6, Issue 8, p. 233 –234
- DOI: 10.1049/el:19700164
- Type: Article
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A z transform factorisation result is developed from the discrete-time matrix Riccati equation, in a similar way to the well known spectral-factorisation result of continuous time systems.
Signal-injection triggering of X band Gunn oscillators for f.s.k. operation
- Author(s): R. Huntington ; H.L. Hartnagel ; P. Bestwick
- Source: Electronics Letters, Volume 6, Issue 8, p. 234 –235
- DOI: 10.1049/el:19700165
- Type: Article
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Experimental results show that the threshold effects of signal-injection triggering of Gunn oscillators can be employed for binary frequency-shift-keyed regenerator operation.
Linearisation of nonlinear systems
- Author(s): C.J. Macleod
- Source: Electronics Letters, Volume 6, Issue 8, p. 235 –237
- DOI: 10.1049/el:19700166
- Type: Article
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It is shown that the application of a technique used in numerical analysis to the problem of linearising nonlinear systems yields linearised responses. The systems considered contain single-valued nonlinearities which can be described by low-order power series.
Multidimensional BIFORE transform
- Author(s): N. Ahmed ; R.M. Bates ; K.R. Rao
- Source: Electronics Letters, Volume 6, Issue 8, p. 237 –238
- DOI: 10.1049/el:19700167
- Type: Article
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The BIFORE transform is generalised to r dimensions. The corresponding power spectrum consists of Πi = 1r(1+ki) spectral points (Nt = 2ki), which are invariant under cyclic shifts of the r-dimensional input data. A physical interpretation of the BIFORE power spectrum is presented.
Van der Graaf's equivalent circuits for series and shunt modulators
- Author(s): D.G. Tucker and D.P. Howson
- Source: Electronics Letters, Volume 6, Issue 8, p. 238 –240
- DOI: 10.1049/el:19700168
- Type: Article
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It is shown that the equivalent circuits used by van der Graaf, while giving perfectly correct results for the problems to which he applied them, lack general validity, even within the conditions assumed by him. In particular they appear to demonstrate that it is possible to obtain a constant input resistance (i.e. constant with respect to time) in a series or shunt modulator, whereas clearly such a result is impossible in reality. An alternative system of equivalent circuits is shown to avoid the difficulty. An explanation is given.
Subharmonically injected phase-locked IMPATT-oscillator experiments
- Author(s): C.H. Chien and G.C. Dalman
- Source: Electronics Letters, Volume 6, Issue 8, p. 240 –241
- DOI: 10.1049/el:19700169
- Type: Article
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Subharmonically injected phase locking of continuously operated IMPATT oscillators has been demonstrated with frequency ratios as high as 9 : 1. The measured locking-range/locking-gain slope for the 2 : 1 case is about 10 dB/ decade of locking range and that for the 9 : 1 case is about 5 dB/decade of locking range.
Novel ratemeter with very wide range
- Author(s): J.M. Griffiths
- Source: Electronics Letters, Volume 6, Issue 8, p. 242 –243
- DOI: 10.1049/el:19700170
- Type: Article
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A digital ratemeter is described which measures event rates over a range of many decades without switching. The smoothing of the results automatically adjusts to the event rate.
Note on the radiation associated with the excitation of an open resonator
- Author(s): A.L. Cullen
- Source: Electronics Letters, Volume 6, Issue 8, p. 243 –244
- DOI: 10.1049/el:19700171
- Type: Article
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Open resonators have a number of possible applications at microwave frequencies; the very high Q factor obtainable is one attraction. Coupling to the resonator usually takes place through small coupling holes in the mirrors. An important practical question is to what extent radiation of energy out of the resonator by these holes limits the Q factor obtainable. In this letter a very simple formula is derived. The effect is shown to be very small.
High-speed phase and amplitude modulation of Gunn oscillators
- Author(s): B. Martin and G.S. Hobson
- Source: Electronics Letters, Volume 6, Issue 8, p. 244 –246
- DOI: 10.1049/el:19700172
- Type: Article
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Linear phase and amplitude modulation of X band Gunn oscillators up to 3 GHz modulating rates has been observed. The modulating signal was applied through the bias circuit, and typical sensitivities were 0.1 rad/V and 10% depth of modulation/volt, respectively. A simple theoretical explanation of the results is given.
Varactor-tuned Gunn-effect oscillators
- Author(s): D. Cawsey
- Source: Electronics Letters, Volume 6, Issue 8, page: 246 –246
- DOI: 10.1049/el:19700173
- Type: Article
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The electronic tuning range of varactor-tuned Gunn-effect oscillators is restricted by the limited Q factor of available varactors. This is relevant to the interpretation of some recently reported results.
A.M. noise of IMPATT-diode oscillators
- Author(s): G. Ulrich
- Source: Electronics Letters, Volume 6, Issue 8, p. 247 –248
- DOI: 10.1049/el:19700174
- Type: Article
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Based on a general oscillator model, noise spectra are calculated by a quasistationary method. From this, the reduction of the a.m. noise caused by adjusting the locus of the load circuit orthogonal to the curve of the device impedance is indicated and verified by experiments. The noise reduction generally is 5–15 dB. Measurements of the a.m.-f.m.-noise-correlation coefficient confirm the results.
Lyapunov matrix equation with complex matrices
- Author(s): H.M. Power and A.C. Tsoi
- Source: Electronics Letters, Volume 6, Issue 8, p. 248 –249
- DOI: 10.1049/el:19700175
- Type: Article
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Rules are given for converting the equation in n×n matrices, A*L+LA = −K, with A complex and K Hermitian, to the form βd = −f, where β is a real n2×n2 matrix and d and f are real column vectors formed from the real and imaginary parts of L and K.
Compensation of injection-laser excess noise by means of an external modulator
- Author(s): G. Guekos and M.J.O. Strutt
- Source: Electronics Letters, Volume 6, Issue 8, p. 250 –251
- DOI: 10.1049/el:19700176
- Type: Article
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An external modulation of a c.w. injection laser is described which allows a strong reduction of the excess noise of the laser beam. KDP was used as a modulator and the modulating voltage was proportional to the noise voltage across the load resistor of the photodetector of the beam opposite the modulated one.
Comment: Synthesis of asymptotically stable linear time-invariant closed-loop systems incorporating multivariable 3-term controllers
- Author(s): B. Porter
- Source: Electronics Letters, Volume 6, Issue 8, p. 251 –253
- DOI: 10.1049/el:19700177
- Type: Article
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The letter contains some elementary observations on a letter in which an inverse Lyapunov technique was propounded as a means for obtaining ‘gain’ matrices in such a manner that a linear 3-term controlled closed-loop system was rendered asymptotically stable. While that letter is rigorously correct in most respects, some simple properties of the constituent matrices were overlooked and others were masked by the adoption of the Lyapunov method.
Lowpass digital filters with linear phase
- Author(s): A.R. Memon
- Source: Electronics Letters, Volume 6, Issue 8, p. 253 –254
- DOI: 10.1049/el:19700178
- Type: Article
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A method of synthetising lowpass recursive digital filters is given in the letter. The method relies on the properties of orthogonal functions on the z plane and the impulse response of an ideal lowpass linear phase filter. Considerable saving in computation and storage appears to have been achieved by this method compared with the nonrecursive (with window functions) truncation method.
Aerial noise-temperature variations due to atmospheric changes at frequencies of 3.95, 11.75, and 17 GHz
- Author(s): E.G. Jarvis
- Source: Electronics Letters, Volume 6, Issue 8, p. 254 –255
- DOI: 10.1049/el:19700179
- Type: Article
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–255
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Aerial noise-temperature variations measured at 5° elevation on continuously recording radiometers of 500 MHz band-width about 3.95, 11.75 and 17 GHz for a period ending in August 1969 are presented as cumulative distribution curves. Measurements are continuing during 1970.
Fully iterative array for extracting square roots
- Author(s): R.C. Devries and M.H. Chao
- Source: Electronics Letters, Volume 6, Issue 8, p. 255 –256
- DOI: 10.1049/el:19700180
- Type: Article
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A cellular array is proposed for extracting square roots. In contrast to an earlier proposal, both the cells and the interconnection of cells are identical.
Complex BIFORE transform
- Author(s): N. Ahmed and K.R. Rao
- Source: Electronics Letters, Volume 6, Issue 8, p. 256 –258
- DOI: 10.1049/el:19700181
- Type: Article
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A complex BIFORE transform is defined and elementary properties of the transform are developed.
Admittance measurements through nonuniform transmission lines
- Author(s): T. Koryu Ishii and J.A. Mashock
- Source: Electronics Letters, Volume 6, Issue 8, p. 258 –259
- DOI: 10.1049/el:19700182
- Type: Article
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For an unknown admittance connected at the end of a continuous nonuniform transmission line, a new simple and straightforward method of admittance measurement is introduced. The method permits the determination of the admittance based on the data measured at the input of the nonuniform transmission line.
Surface-wave radiation from a corrugated horn
- Author(s): R. Baldwin and P.A. Mcinnes
- Source: Electronics Letters, Volume 6, Issue 8, p. 259 –260
- DOI: 10.1049/el:19700183
- Type: Article
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An expression for the radiation pattern of a surface-wave antenna given by Andersen has been checked experimentally by considering the radiation from the finite aperture of a corrugated horn which supports only a slow hybrid mode
Use of high-relative-permittivity materials in high-delay coaxial lines
- Author(s): A.J. Pointon and K.F. Woodman
- Source: Electronics Letters, Volume 6, Issue 8, p. 260 –261
- DOI: 10.1049/el:19700184
- Type: Article
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The delay characteristics of a common type of electromagnetic delay line are considered as both an unshielded line and a shielded line filled with materials of high relative permittivity.
Multiform total symmetry and parity functions
- Author(s): S.R. Das
- Source: Electronics Letters, Volume 6, Issue 8, p. 261 –262
- DOI: 10.1049/el:19700185
- Type: Article
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In recent letters, Biswas reported the existence of a special class of totally symmetric switching functions which remain invariant for all combinations of complemented and uncomplemented variables of symmetry, and also studied some of their properties. It is shown in this letter that these special symmetric functions are a particular class of linear functions known in literature as odd-parity functions and even-parity functions and form a subclass of totally symmetric functions showing multiform symmetry. Some of the relevant properties of these functions from the viewpoint of linear functions are also studied.
Surface waves at ferrite-metal boundaries
- Author(s): R.A. Hurd
- Source: Electronics Letters, Volume 6, Issue 8, p. 262 –264
- DOI: 10.1049/el:19700186
- Type: Article
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A study is made of the conditions under which a surface wave may exist in a ferrite which is separated from a perfect conductor by a thin layer of a different ferrite. It is found that the properties of the thin layer have a pronounced effect on the form of the wave, even when the thickness is allowed to shrink to zero and the surface wave becomes degenerate.
Signal flowgraphs solved by graph-expansion algorithm
- Author(s): J.C. Polasek
- Source: Electronics Letters, Volume 6, Issue 8, p. 264 –265
- DOI: 10.1049/el:19700187
- Type: Article
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A new algorithm for the solution of signal flowgraphs by Mason's rule expands the graph into a tree, exposing every possible path and loop. Set theory then locates nontouching pairs and higher orders.
Rapid generation of Bessel functions required for solutions to engineering problems
- Author(s): A.J. Hissink and B.R. Gladman
- Source: Electronics Letters, Volume 6, Issue 8, p. 265 –266
- DOI: 10.1049/el:19700188
- Type: Article
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An efficient computer subroutine for the generation of an array of Bessel functions of the first and second kinds for a given argument and all orders up to N has been written. It is faster, more accurate, and will work over a wider range of orders and arguments than the normally available IBM system/360 subroutines.
Erratum: Method of generating low-sensitivity RC active circuits
- Author(s): A.E. Robinson and A.E. Methiwalla
- Source: Electronics Letters, Volume 6, Issue 8, page: 267 –267
- DOI: 10.1049/el:19700189
- Type: Article
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